In a Long Term Evolution (LTE) system, when the network side schedules data transmission, Downlink Control Information (DCI) may carry Modulation and Coding Scheme (MCS) Information. Also, the network side and the terminal side previously agree a mapping relationship between MCS indicated by indication information and a Transport Block Size (TBS). The terminal device can know about the corresponding TBS for data transmission to and from the network device according to the indication information and the mapping relationship.
Currently, the correspondence between TBS, MCS, and PRB resources is determined under the assumption of a fixed resource overhead which includes resources occupied by the control channel and resources occupied by Cell-specific Reference Signals (CRS). However, in a 5G system, or know as a New Radio (“NR”) system, there are many factors affecting the overhead, including: different resources occupied by the control channel; High Reliable and Low Latency Communications (“URLLC”) traffic added into enhanced Mobile Broad Band (“eMBB”) traffic; different Channel State Information-Reference Signals (CSI-RSs); the number of antenna ports (including the number of ports that are invisible to some terminals); a density of different Demodulation Reference Signals (DMRSs).